Wolfgang Amadeus MOZART (1756-1791). Autograph musical manuscript, [ca. 1783]; 1 oblong page in-4 (20.5 x 28 cm, verso blank); in antique folder with calligraphic blue paper label Original manuscript by W.A. Mozart. Beautiful page of sketches for two canons and a trio. [KV Anh. H10, Nr.14 and KV 686] An oblong sheet written on the front in brown ink; 10-line paper. It is listed in the Neue Mozart Ausgabe (X/30/3) as Skb 1783f, and dated by Ulrich Konrad to c. 1783 or later. The top of the folio is occupied, on three staves, by a 3-voice canon in C (soprano, tenor and bass), at 2/2 (barred C) in 12 bars [Skb 1783f/1a]; it is followed by another 2-voice canon (soprano and bass) on the same theme in 9 bars [Skb 1783f/1b; Köchel-Verzeichnis (2024) KV Anh. H10, Nr.14]. On the next three staves, Mozart sketched 29 bars of a trio (Triosatz) in C minor, probably for two violins and cello, in 4/4 (C), the last six bars notated on two staves. [Skb 1783f/2; KV 686]. At bottom right, Mozart has aligned zeros four times. The folio is authenticated at the bottom by Aloys FUCHS: Die Aechtheit dieser Mozartschen Handschrift bestättigt hiermit Aloys Fuchs. [Originally from Moravia, Aloys Fuchs (Rázová 1799-Vienna 1853) came to Vienna in 1816 to study philosophy and law at the University. He quickly made friends with many composers and artists, including Beethoven, Mendelssohn and Schumann. His employment at the War Ministry did not prevent him from devoting all his spare time to music: he was a talented cellist, gave musical soirées, and in 1836 joined the Imperial Court Chapel Choir. Above all, he applied himself passionately to musicology, compiling vast documentation on Viennese musicians, especially Mozart, and recovering some of the manuscripts from his estate, which he made available to Köchel for his reference catalog of the composer's works, and which he used as currency to enrich his collection. Europe's first systematic collector of musical autographs, a learned and tireless amateur, his aim was to build a universal music library: from 1817 to his death, he assembled the most important private music collection of his time, including not only the most prestigious German and Austrian names, but also virtually all the names of European music. Fuchs made substantial donations to the Gesellschaft der Musikfreunde in Vienna, of which he was a member, forming a valuable part of that institution's treasures. On his death, a significant part of his collection was acquired by the Deutsche Staatsbibliothek in Berlin, and by other institutions]. The manuscript is accompanied by a letter from Aloys Fuchs, signed Louis Fuchs, dated February 28, 1842 (1 page in-8 in French), to the famous cellist Adrien-François Servais (1807-1866): Ardent to respond to the wish of which you have spoken to me, I hasten to offer you an autograph of Mozart, asking you to accept it as testimony of the most perfect appreciation of the art with which you delight us. If, at the same time, you would honor me with a few lines of your own, you would satisfy my most fervent desire... [Servais sent Fuchs an excerpt from his Fantaisie romantique, dated 1842, which Fuchs included in his Musikalisches Album zur Erinnerung an günstige Freunde (p. 84; no. 1192 of the 7th Aristophil sale)]. In the upper left-hand corner of the Mozart folio, Servais inscribed his monogram S, repeated on the cover [Adrien-François Servais (1807-1866), nicknamed the Paganini of the cello, was the father of composer Franz Servais (1846-1901), and the grandfather of Misia Godebska (1872-1950), the future Misia Sert]. Provenance: [Constanze Mozart (1762-1842) or her estate]; Aloys Fuchs; Adrien-François Servais (1807-1866); his daughter Augusta (1860-1925), wife of tenor Ernest Van Dyck (1861-1923); then descendants. [See nos. 11 and 214-216. References: Ulrich Konrad, Mozarts Schaffensweise. Studien zu den Werkautographen, Skizzen ud Entwürfen (Göttingen, 1992): pp. 249-251 and 312. - Neue Mozart Ausgabe X/30/3 (1998), p. 50; and Kritische Berichte (1998), pp. 27-28. - Köchel-Verzeichnis (new edition, Bärenreiter 2024), KV 686 and KV Anh. H10, Nr.14. We would like to thank Mr. Ulrich Leisinger for the information he provided. Attached is a countertype photograph of Adrien-François SERVAIS with his cello in its case (reproduced lower left, p. 103).